Valorisation of coal gasification slag and fly ash to mesoporous activated carbon @zeolite socony mobil-5 composite for preconcentration of pharmaceuticals and their removal

Abstract

Upcycling industrial solid waste, such as coal gasification slag and fly ash, to functional adsorbents with unique structures for water decontamination is of great importance to achieving Sustainable Development Goal 6.0. This study used coal gasification slag and fly ash to synthesise mesoporous activated carbon @zeolite socony mobil-5 (MAC@ZSM-5) composite. Various analytical techniques were used to investigate the surface, morphological, and structural properties of the MAC@ZSM-5 composite. The MAC@ZSM-5 composite had a relatively high specific surface and was classified as a mesoporous adsorbent. The MAC@ZSM-5 composite was used as an adsorbent in ultrasound-assisted micro solid phase extraction (UA-µSPE) for effective preconcentration and removal of aspirin (ASP), ibuprofen (IBP), and paracetamol (PCT) from water samples before determination by high-performance liquid chromatography equipped with a photodiode array detector (HPLC-DAD). The Langmuir adsorption isotherm characterised the adsorptive removal method, while the kinetics followed a pseudo-second order type. Thermodynamic studies revealed that the adsorption process was endothermic, spontaneous, and chemisorption. Additionally, the UA-µSPE/HPLC-DAD method displayed a good linear range of 0.1–1000 µg/L, with a coefficient of determination greater than 0.99. The developed method had a good performance, as shown by the relatively low limits detection (LODs: 0.017–0.064 µg/L) and quantification (LOQs: 0.057–0.21 µg/L) as well as high precision (relative standard deviation (%RSD) < 5 %). The proposed method was applied successfully for preconcentration and removal of the target analytes from real water samples. The MAC@ZSM-5 composite was reusable (up to 5 cycles) and proved a promising adsorbent for effective extraction, preconcentration, and adsorptive removal of emerging contaminants from water bodies.